Circuit interrupter



April 5, 1955 H. H. MITCHELL CIRCUIT INTERRUPTER 4 Sheets-Sheet 1 Filed 001;. 13, 1952 [M/EA/TQ/P: f/ApoLp H. MITCHELL April 5, 1955 Filed Oct. 13, 1952 H. H. MITCHELL CIRCUIT INTERRUPTER 4 Shets-Sheet s April 5, 1955 H. H. MITCHELL CIRCUIT INTERRUPTER m m 2 e w .0 Q i w mw m a A m I. s m F. s i mm a, 5 z w a J :2 W s W W 1 7 7 Z M E 6 M m w: i 1:? Q A v g 9 mm m Z w mm 3 w a z o iw a United States Patent 0 tactsbeing immersed in a dielectric fluid. Wlth the increased concentration of breakers of the circuit-breaker and within required Notwithstanding the requirements necessary of large-capacity circuit-breakers that the present invention may accommodate, the structure herein is simimally large magnitude or amplitude, they might, at times, interrupt relatively small currents. Accordingly, when a circuit therethrough is interrupted the are drawn between the gap intermediate the separating contacts may a relatively large expanding generated under conditions of low-current interruption to develop a surge adequate to extinguish the small are drawn intermediate the interrupting contacts. It is an object of the present invention, therefore, to provide a novel circuit-breaker that is capable of effectively interruptmg currents of various magnitudes.

Generation of heat in circuit-breakers is a continuous problem, particularly the localization of heat adjacent the engaging contacts. The present invention contemplates a practical and economical and novel system to minimize the problem aforesaid by positioning the arcquenching member or members in such a manner and in such relation to other components as to permit a flow of dielectric fluid to continuously lave the engaging contacts whereby the heat may be conveyed away from the location of localization, and it is an object of the present invention to provide such a system.

Another object of the invention is to provide an arcquenching member, or plurality thereof, for mounting in a space containing a dielectric fluid whereby the space may be of a lesser volume than that of comparable conventional circuit-breakers of whereby the diameter or maximum horizontal dimension of the main housing therefor may be substantially reduced.

Another object of the invention is to provide a novel arc-quenching member and linkage means for actuation of the contacts therefor whereby accessibility for inspec- Another object is to provide a pump means incombination and integral with an arc-quenching member whereby a surge of dielectric fluid may be directed to the interruptmg contacts in the absence of an electrically generated fluid blast.

with, interengaged so that an adequate surge of dielectric fluid may be directed to the interrupting arc gap to quench b nother object to provide an arc-quenching memcharacteristics which permit the precipitation or is a with carbon particles a pump means chanically induced surge of fluid.

It is a further object to provide an arc-quenching member with a pump means integral therewith for producing a surge of dielectric fluid longitudinally of the member, tire ptllilmp means being valved to permit a flow of fluid t ere stantially direct compression force against the conductor insulating bushing.

It is another object to provide an arc-quenching member having the above characteristics in which gas remaining within the member subsequent to the circuit interruption cycle may be scavenged therefrom.

The present invention also has for its objects to provide by way of illustration or example only.

In the drawings, like reference characters designate similar parts in the several views, wherein:

Fig. 1 is a vertical cross-sectional view of a complete circuit-breaker embodying the invention;

Fig. 2 is a front elevational view of one of the arcquenching members and associated components;

Fig. 3 is a side elevational view of the arc-quenching member, partially in section, taken along the line 3-3 of Fig. 2, and illustrating a pair of contacts in the closed position;

Fig. 4 is a side elevational view of the arc-quenching member partially in section, taken along the line 44 of Fig. 2 and illustrating a pair of contacts in a position assumed during the circuit-interrupting cycle;

Fig. 5 is a cross-sectional view of a fragment of the member, taken along the line 55 of Fig. 4, but illustrating the contacts in a later-assumed position during the current interruption cycle;

Fig. 6 is an enlarged cross-sectional view of the fluid current-conducting engagement;

Fig. 7 is a partial sectional view of a fragment of Fig. 6 showing the pump in one possible position during the current interruption cycle;

Fig. 8 is a sectional side elevational view of a portion of the pump taken along the line 8-8 of Fig. 7;

Fig. 9 is an end view of the pump taken along the line to as the generating contacts and the second pair as the 99 of Fig. 6; interrupting contacts. It is to be understood, however, Fig. 10 is a slightly enlarged cross-sectional view of that the present disclosure contemplates the use of addithe arc-quenching member, taken along the line 10-10 tional pairs of contacts in spaced relation longitudinally of Fig. 4, and illustrating the baffle arrangement and of the passage 42 and which may be similarly operative longitudinal passages formed thereby; as the contacts abovementioned. It is to be further Fig. 11 is a sectional view of a portion of the arcunderstood in this connection that the structure, for exqu n hing member, taken along the li e 1 of Figample, as illustrated in Fig. 4, is submerged in its entirety and showing a baffle and spacers therefor in relation in the dielectric fluid. to one contact member of two pairs of such members; 10 Each of the contacts 51, 52, 53, 54, etc., is mounted Fig. 12 is a sectional view of the arc-quenching memto the tubular member 40 in a similar manner as by reber taken along the line 12-12 of Fig. 10-and showing traction means generally indicated by the numerals 56, a baflle in relation to one contact member of two pairs 57, 58, 59, etc., respectively, all of the retraction means of such members; and preferably being interconnected by an interengaging Fig. 13 is an electrical schematic of one of the circuits 15 means to be hereinafter described for simultaneous or that may be completed through the circuit-breaker. near simultaneous displacement of the contacts with re- Referring particularly to Fig. 1 there is illustrated a spect to the tubular member 40. It is significant to complete circuit-breaker including a housing of any presently note that the interengaging means is also operageneral peripheral configuration adapted to mount one tive to interconnect the retraction means with the operaor more conductor insulating bushings 21 which extend 20 tive members of the pump means. substantially vertically as shown and down into a space For purposes of description, reference is made to one 22 that contains a dielectric fluid. The lower end 23 of of the contacts and its retraction means, for example, as each bushing 21 preferably extends down and into the designated by the numerals 51 and 56, respectively, as fluid and has attached thereto an arc-quenching member best seen in Figs. 2 and 4. The contact 51 is shown generally indicated by the numeral 25. 25 as extending radially of the tubular member and there- The circuit to be completed through the circuit-breaker through, being slidably receivable in an annular bearis connected to conductor terminals 27 of the bushings ing 61, the bearing being rigidly secured in and encom- 21, the circuit being conducted through each bushing, passed by an aperture 62 in the tubular member 40. through each arc-quenching member 25 and to a con- The bearing is provided with a flange 63 at one end tact blade or bridging member 28 which member is com- 0 thereof which is receivable in a counterbore portion 64 mon to both circuits aforesaid. A lift rod 29 is secured of the member 40, the opposite end being threaded to to the center of the blade 28 and is adapted to reciprocally receive a retainer ring 66. Firmly secured intermedimove the blade from the position shown to a phantom ate the ring 66 and the tubular member 40 is a wall 67 position indicated by the numeral 28a for interruption of a frame 68 which is suitably apertured as designated and/or completion of the circuit. The lift rod is actu- 5 by the numeral 69, the frame serving to mount the reated by a tripping mechanism (not shown) that may be traction means 56 for the contact member 51. of the conventional type, means for actuation therefor Each retraction means 56-59, inclusive, and its correextending by suitable linkage means to a dome member sponding contact member, is similar to the others with indicated by the numeral 31 centermost of the housing. possible dimensional exceptions that will be hereinafter The structures on either side of the bridging member 40 explained whereby sequential, as opposed to simulta- 28 are identical. Accordingly, only one side may be neous, interruption of contacts may be effected. Rediscussed in detail for a full understanding of the present ferring to Fig. 3, each contact member comprises an invention. elongated rod 70 preferably circular in cross section and The conductor insulating bushings 21 are generally includes an engaging cap or tip 71 for contact with the tubular in construction and are mounted substantially mating contact member, the tip being preferably made of normal to the top of the housing generally indicated by an arc-resistant material such as tungsten silver alloy. the numeral 32, the top being lllustrated as dome-shaped The rod is provided with a coaxial bore 72 extending in its preferred form. An overhanging flange 36 exsubstantially the length of the rod and which terminates terior of the housing peripherally engages the insulating adjacent the end thereof to which the tip 71 is secured. bushings 21 for locking securement thereof to the top of Disposed within the bore is a resilient element 73 illusthe housing 32. The arrangement for securing the contrated in the form of a compression coil spring and a ductor insulating bushing to the housing provides a slide 74 which is adapted to be reciprocally translatable means to rigidly position the attached arc-quenching in the bore. The slide is provided with a transverse openmembers for maintaining alignment of the latter within ing 76 extending completely therethrough and also is the space 22. provided with an axial bore 77 which is partially threaded Referring to Figs. 2, 3 and 4, there is illustrated the to receive a screw 78. arc-quenching member 25 in various operative posi- Intermediate the ends of the contact member and cut tions. It is preferably constructed of alongitudinal tubufrom the wall thereof there is provided a pair of oplar member 40 made of insulating material embracing a posed slots 80, 81 (see Fig. 4) extending longitudinally zone 41 within which the contacts, to be described hereof the contact member communicating the bore 72 to inafter, are engaged and separated. A longitudinal pasthe exterior of the rod 70. The contact member is intesage 42 extends the length of the member 40 but is grated with the slide by means of a bar 82 of sufficient preferably divided into a plurality of baffle passages length which extends through the slots 80, 81 and the 43 the formation of which will be hereinafter explained. opening 76 of the slide. The screw 78 serves to secure The member 40 has an upper end 44 which is secured to the bar rigidly to the slide. The physical dimensions of a pump means generally indicated by the numeral 46, for the slots 80, 81 and the bar 82 are such that the slide example, as by threading, as indicated by the numeral is translatable in the bore 72, the movement therein 47 (see Fig 4). The assembly is provided with abuttress being limited by engagement of the bar with the slot plate 48 at 1ts uppermost end which is preferably slightly extremities, for example, the extremities indicated by the angularly disposed, as illustrated, and rigidly secured to numerals 83 and 84, as best seen in Fig. 4. In a prethe lower end of the substantially vertical conductor 1nferred construction, the tolerances of manufacture are sulating bushing 21 in any conventional manner. The held sufiiciently close that the bar 82 contacts the reslight inclination of the bushings 21 with respect to spective extremities of the slots simultaneously. The each other, while substantially vertical, provides sufficient spring 73 which extends intermediate the end of the spacing between the conductor terminals 27. Also, the bore 72 and the slide 74 is designed to be compressed slight angular displacement of the insulating bushing 21 when the slide 74 is translated toward the tip 71 of with respect to its arc-quenching member 25 maintains the contact member. There is thus provided alost-motion a substantially in-line correlation whereby reactive force connection intermediate the contact member and the caused by fluid blast is directed in compressive relation bar 82, the latter element of which may be deemed to the insulating bushing. a part of the retraction means.

The arc-quenching member as illustrated is provided The retraction means for each contact member is prefwith two pairs of contacts, an uppermost pair designated erably constructed as a balanced type, that is, the actuatby the numerals 51 and 52, and a second pair therebeing mechanism is double-linked, as will hereinafter be low designated by the numerals 53 and 54. For purposes explained. However, it is contemplated that a singleof convenience the first-mentioned pair may be referred 85 link mechanism may be employed. Referring to Figs. 2

122 and surrounding each of the and 3 the bar 82 is shown as having connected to its opposite extremities a pair of first links 86 which are in pivotal relation to the bar. The opposite extremities of the links 86 are each pivotally connected as indicated by the numerals 87, respectively, to a pair of second links 88, the latter of which terminate at one end by a pivotal connection as indicated by the numeral 89 to the frame 68. Each of the links 86 is provided with an aperture 91 intermediate its ends which receives a connecting shaft 92, the shaft having pivotally connected at its opposite ends a pair of extending arms 93, 94 of a yoke 95. The yoke, as best seen in Fig. 2, is rigidly secured as by a hub 97 to a shaft 98, all of which are adapted to be angularly displaced about an axis defined by a pair of aligned shaft receiving means 99, as best seen in Fig. 2, which are located in fixed relation to the frame 68. Rigidly connected to one end of the shaft 98 is a crank arm 101, the arm in turn pivotally linking as indicated by the numeral 102 to an interengaging link 103.

The linkage means thus far described for one contact member and the retraction means therefor is similar to the other three linkage means illustrated in the drawings. Alternative modifications as between linkage means are contemplated, however, which will hereinafter be explained.

An interengaging means is provided to integrate the cyclic movement of all of the contact members and includes an actuating slide bar 105 which is made of insulating material and which is preferably mounted with relation to the tubular member and the pump means 46 in such a manner as to be reciprocally translatable along a line generally parallel to the member 40. Each of the interengaging links is pivotally connected as indicated by the numeral 107 to the slide bar whereby translation of the slide bar through the medium of the link 103 and the arm 101 will cause angular displacement of the yoke 95.

The slide bar 105 while serving as part of the interengaging means for the retraction means and pump means is the primary tripping element for the arc-quenching member as well as serving as a mount for one of a supplemental pair of contacts to be interrupted during the current interruption cycle. Referring to Figs. 2 and 3 guide means are provided for the lower end of the bar comprising a pair of downwardly extending legs 110 and a retainer plate 111 both of which are secured to each other and to the tubular member 40 as by a plurality of screws 112. Attached to the lower extremity of the slide bar 105 is a foot 113 made of current-conducting material and having an upstanding leg engagement with the slide bar and being by means of screws 115. As best seen in Fig. 3, one end of the bridging member 28 is disposed between the legs 110 and is provided with a current-carrying contact 116 which is adapted to engage the foot 113 to complete the electrical circuit to be hereinafter described. As the bridging member 28 is vertically translated the contact 116 thereof is adapted to urge the foot 113 upwardy with a resultant upward motion of the slide bar 105. It is to be noted that when the circuit-breaker is in a tripped position the bridging member is preferably vertically displaced sufiiciently below the legs 110 to provide sufiicient spacing from the foot 113 when the slide bar is in the lowermost position. The legs 110 are provided with an opening-downward flare at the lower extremities thereof as designated by the numerals 119 which serves as an alignment guide for the bridging member 28 when it moves upwardly and into engagement with the foot 113.

Referring to Fig. 3, the upper end of the slide bar 105 is provided with a head 120 secured thereto as by rivets 121 and which includes a pair of oppositely disposed guide bosses 122, each boss having a vertically disposed threaded bore 123 to receive an upstanding tube 124. The head also includes a yoke generally indicated by the numeral 125 comprising two upwardly extending legs 126 joined at their extremities by a hub 127, the hub supporting a shaft 128 therein which extends outwardly of the hub at its extremities for pivotal connection with a pair of links 130.

Secured to the buttress plate 48 and extending downwardly therefrom and into slidable engagement with the tubes 124 are a pair of shanks 132, respectively. Intermediate the under side of the plate 48 and the bosses engaged tubes and shanks secured thereto 114 for tongue therefor is disposed a resilient member of a compression coil spring, to normally urge the slide bar 105 in a downward and circuit-interrupting direction. The spring 133 may be appropriately designated as an accelerating spring for positive actuation of the bar 105 as will become apparent hereinafter.

Referring now to Figs. 6 to 9, inclusive, wherein the pump means 46 is clearly illustrated, the buttress plate 48 is shown as being substantially circular in plan and slightly angularly disposed from the horizontal being provided with a series of columnar supporting members 136 extending downwardly and which are secured to a base 137 as by a plurality of studs or bolts 138, the connection being made in such a manner so as to maintain the columnar members 136 in rigid relationship to the base 137 thereby providing a rigid assembly intermediate the tubular member 40 and the conductor insulating bushing 21, the latter of which is firmly secured at its lower end in planar abutment with the upper face of the buttress plate 48.

The pump means is provided with a cylinder 140 open at both ends and which is threaded as indicated by the numeral 47 into the tubular member 40. The base 137 has a central opening therethrough of sufiicient size to receive the upper end of the cylinder 140 whereby the base may firmly abut the upper end of the tubular member 40, the engagement being maintained by means of an internally threaded retainer ring 141 threaded onto the extremity of the cylinder 140 and into surface engagement with the base 137.

Slidably receivable in the cylinder 140 is a piston 142 which is adapted upon downward movement to decrease the volume of the passage 42. As best seen in Fig. 8 the piston is preferably cup-shaped having a base 143 and an integral upstanding peripheral wall 144, the wall being circular in its preferred form and including a plurality of compression rings 145 thereabout. The piston is provided with a vent means and closure means therefor, the preferred structure being including a flue which maybe in the form of a plurality of orifices 133 in the form the function of which is vertical direction for surface engagement with the under side of the base 143 whereby to seal the flue.

The plate 148 is preferably circular in configuration and is provided with an annular depression 150 in the upper surface thereof which is concentric with the center of the plate whereby the orifices 147 are not individually sealed when the plate is in engagement with the piston base 143, as best seen in Fig. 8, but are in communication with a space 151 defined by the depression 150 and the piston base 143.

Supporting and maintaining the plate 148 in operative position with respect to the piston is a bolt 152 having a shank 153 threaded at the upper end thereof, a slightly enlarged shoulder 154, and a flange 155, the latter serving as a seat for the plate when the plate is in the lowermost position, as best seen in Fig. 6. The shank of the bolt extends through a bore 156 in the center of the base of the piston and through a bore 157 in the base of a cupshaped retaining member 158, a nut 159 being threaded onto the shank so as to rigidly affix the piston to the member 158. The plate 148 is provided with a central hole 161 of a diameter slightly greater than the diameter of the shoulder 154 whereby the plate is free to rotate and reciprocate about the longitudinal axis of the bolt. Further, the thickness of the plate is slightly less than the axial height of the shoulder 154 whereby the plate may reciprocally move in a vertical direction from the position illustrated in Fig. 6 to a position illustrated in Fig. 8 for alternate opening and closing of the orifices 147. Thus a valve means is provided at the upper end of the passage 42 intermediate the passage and the space 22 thereover the function of which will be hereinafter described.

Disposed in the well of the cup-shaped member a yieldable element 163 illustrated in the form of a pression coil spring which extends upwardly and cominto

of the spring 163 is an cavity defined by the second tube 165, the tubes 164 and 165 cooperating to maintain the coils of the spring 163 in aligned position during compression and extension thereof.

Referring to Fig. 8, the member 158 is provided with a pair of studs 167 extending outwardly and providing a pivot means for a pair of links 168. Each of the links, one of which is best seen in Fig. 7, is provided with an elongate slot 169 therethrough providing a range of limited slide motion of a pin 170 receivable therein, the motion being limited by the upper and lower extremities of the slot, as indicated by the numerals 172 and 173, respectively. The pin 170 is rigidly secured to one end of an arm 175 the other end of which is pivoted as by a stud 176 to a downwardly extending ear 177 formed integrally with the buttress plate 48. Intermediate the ends of the arm 175 there is provided a bore 178 adapted to receive a pin 179 that is freely rotatable therein, the pin extending laterally of and being rigidly secured to an intermediateportion of the link 130. As hereinbefore described, the

link 130 is pivotally connected at one end to the shaft 128 of the upper end of the head 120. The other end of the link 130 is preferably connected as indicated by the numeral 181 to one end of an idler link 182, the linkage terminating by pivotal connection to the other end of the link 182 as by means of a shaft 183 to a pair of legs 184 which extend downwardly from the under side of and preferably integral with the buttress plate 48.

The linkage lastly hereinabove described may be duplicated on both sides of the piston, as is illustrated in the drawings, in order to effectuate a balance of forces. This linkage is provided for actuation of the piston and may be now understood as connected to the interengaging means for actuation in cooperation with movement of the slide bar 105. As will be hereinafter understood, the operative relation of each of the links 168 and the arms 175 provides effective range of lost motion therebetween.

Referring to Fig. l, the circuit to be interrupted is connected to the conductor terminals 27 at the upper extremities of the conductor insulating bushings 21. Each bushing is provided with the usual conductor (not shown) extending the length of the bushing and which is conductively secured in any conventional manner to the buttress plate 48. The buttress plate and columnar members 136 are constructed of conductive material, the circuit being communicated thereby to a pad 190, as best seen in Figs. 9 and 3, to which is secured a conductor generally indicated by the numeral 191. The conductor 191 comprises a plurality of individual flexible conductors 192 in parallel, as best seen in Fig. 2, providing flexibility thereto, the ends of the conductors 192 being suitably embedded in end terminals therefor designated by the numerals 193 and 194, respectively. The terminal 194, as indicated on the upper right-hand portion of Fig. 3, is associated with its respective contact member in a manner similar to the others; hence, only one need be described. Referring, Fig. 3, the contact 54 is illustrated as having secured to the outer end thereof a cap-like member 196, one element of which is the terminal 194. The terminal is provided with a bore 197 partially therethrough and is secured in abutment with a plate 198 as by means of screws 199. The plate 198 is similarly provided with a bore 200 therethrough so as to permit the slide 74 upon movement toward the terminal 194 to extend if desired into the cap member 196.

The current path may now be understood as passing in series through the engaging contact members 51, 52, 53 and 54 and other additional pairs of contact members that may be included, the communication intermediate adjacent pairs of contacts comprising, for example, a conductor 202 which is movable in its entirety as dictated by the movement of the individual contact members. As hereinbefore indicated, the conductor 202 is similar in construction to the conductor 191 comprising a plurality of individual flexible conductors terminating at either extremity by a terminal similar in construction to the terminal 194.

The last contact in the electrical series, for example, in the illustration shown as contact 54, is communicated as by a flexible conductor 204 to the foot 113. When the bridging member 28 is at its uppermost position the contact 116 thereof is in conducting engagement with the foot, the blade constituting the medium for carrying the current to the other arc-quenching member for communication therethrough in a similar manner as above described to the terminal 27 thereof.

therefore, to the lower right-hand portion of Fig. 13 is a schematic of the electrical circuitry of the circuit-breaker as described. It is noted, that in certain usage it is desirable to bridge the contacts of a circuit-breaker with grading resistors of predetermined ohmage. Fig. 13 illustrates the place of connection of two grading resistors 206 and 207, the physical counterpart of one thereof being illustrated in Fig. 2 in phantom and which is mounted in any suitable manner to the arcquenching member 25. Electrical conductors as designated by the numerals 208 and 209, also indicated in phantom in Fig. 2, may be connected to the extremities of the grading resistors, for example, as to the pad 190 at the upper end of the arc-quenching member and to the foot 113 at the lower end thereof, the conductor 209 being flexible for movement with the foot. It is also contemplated that the grading resistors may be bridged across individual pairs of contact members, the connections being suitably made as by flexible lines to the terminals 194 of the corresponding contact pairs.

Referring to Fig. 10, the tubular member 40 is shown in cross section illustrating the manner in which the longitudinal passage 42 is divided into a plurality of bafiled passages 43. Separating each passage is a baffle plate 215 which extends substantially the length of the passage 42, the general configuration of the plate 215 being best illustrated in Fig. 12. Each plate 215 is provided with contact-receiving openings 216 and 217 which receive the pairs of generating and interrupting contacts, respectively.

The plates 215 are maintained rigid and separated from one another by a plurality of pairs of spacers 219 having a configuration preferably as illustrated in Fig. 11 and which extend inwardly from the inner wall of the tubular member and defining in conjunction with the baflles 215 the passages 43 aforesaid. The various plates and baffles are arranged in alternating stacked superimposition and are assembled within the member 40, being retained therein in any conventional manner, preferably by means of a plurality of fibrous dowels 221 extending through the batfles and spaces, the outer configuration of the assembly being generated to be firmly retained within the tubular member 40.

The passages 43 as defined at their sides by the spacers 219 comprise a throat 223 at the upper end of the member 40 communicating with a longitudinal passage 224 as defined by a pair of walls 225, a pair of expanded chambers 226 in restricted communication through a port defined by a pair of transverse projections 227 of the spacers, and an outwardly expanding throat 228 defined by a pair of walls 229 and communicating with the space 22 exterior of the arc-quenching member 25. When the contacts are in position within the openings 216 and 217 sufiicient space is provided intermediate the contacts and the adjacent walls of the spacers to accommodate a flow of dielectric fluid through the passages 43. As the fluid may pass through all of the passages 43 a substantial flow may pass through the longitudinal passage 42.

Operation When a signal is received by the master tripping mechanism to initiate a current interruption cycle, the lift rod 29 is caused to move rapidly downward causing the bridging member 28 to move from the uppermost to the lowermost position, as best seen in Fig. 1. During this time interval the actuating slide bar of each arc-quenching member moves downwardly, the foot 113 at the lower end thereof being maintained in engagement with the contact 116 of the bridging member due to the force exerted by the accelerating springs 133 upon the head at the upper end of the bar 105. Accordingly, throughout the initial translation of the lift rod and bridging member, electrical contact is maintained between the foot 113 and the contact 116.

When the circuit-breaker is conducting current the components assume a position as illustrated in Figs. 2 and 3. In this state the slide bar is in the uppermost position compressing the accelerating springs 133, and through the pump means linkage the pin is in abutment with the extremities 172 of the slots 169 to cause the piston 142 to assume a position as illustrated in Figs. 3 and 6. Normally, therefore, the piston is urged downwardly under the influence of the yieldable means that includes the spring 163. Also, through the interengaging means and the retraction means of each contact member 51 to 54, inclusive, the tips 71 of each of.

both of the generating pair of contacts and the interof contacts are in current-carrying engagement being maintained thereby under the slide 74 and partial It may now be understood any disfigurement, burning, pitting, or otherwise, of the tip 71 that results in a small dimensional change of the length of the contact member is subject to compensation therefor by means of the lost-motion connection intermediate the retraction means and the contact member.

Referring now to Fig. 4, the arc-quenching member is illustrated in an intermediate interrupted position during the interruption cycle. downward movement of the slide bar 105 the motion is transmitted to each contact member via the link 103, the arm 101, the yoke 95, the links 86 and to the slide 74 engagement until the bar 82 engages the extremities 34 of the slots 80, 81 whereupon the linkage assumes direct operative engagement with the contact member per se to progressively withdraw it from the zone 41 of the tubular member 40.

centermost portion of the tubular member 40 thus minibearings 61. he contact members 51 and 52 are lllustrated 1n the preferred positions at the their transverse separating motion, being substantially.

41 However, when the coneach arc-quenching member are separated, additional break in the electrical circuit exterior of the arc-quenching member.

e pump means 46 disposed at the upper end of the arc-quenching member provides a physical means to induce a surge of fluid downwardly through the passage 42, and it is actuable through the medium of the interby interconnection with the slide to Fig. 6, the slide bar 105 is illusthe links 130, the slotted links 168, the latter links supporting the pisuppermost position and is connected via Upon the first increment of 1O 1 base 143 of the piston and through the plurality of orifices 147 therein and to the space exterior of the tubular member 40.

As the components in dielectric fluid and wh excess of the thermal fio During the interruption cycle and when the mating pairs of contacts begin to separate forming a gap there- 42. As this electrically induced surge progresses uppassages 43 of foreign material, for example, products of combustion.

Due to the novel means of mounting the arc-quenching member heavy foreign particles will be permitted to precipltate down through the member 40 tion with respect to the bolt 152. Thus, the arc-quenching member may be effectively scavenged of all foreign materials. Maintenance, cleaning, and replacement of component parts of the arc-quenching member are correspondingly reduced notwithstanding the reduction of curtailed operation therefor.

Although the circuit-breaker herein is designed for interruption of currents of a predetermined maximum magnitude, it is necessary that it be capable of interrupting currents of lesser magnitude and within a relatively short period of time. In the interruption of a relatively small current the arc drawn between the gap of the generating contacts may not be of suflicient intensity to generate a fluid blast adequate to extinguish the arc at the interrupting contacts. The pump means in addition to its other functions as aforesaid serves to provide a physically induced surge of fluid toward all of the gaps in the arcquenching member to rapidly and effectively extinguish arcs generated by such small currents. The interruption cycle is completed as hereinbefore described, the upwar flow of fluid or downward motion of the piston 142 causing a closing of the flue. As the upward reaction of the fluid flow due to the relatively small pressure of gas generated is relatively small or negligible, the spring 163 will cause the piston to move downwardly in synchronism with downward movement of the actuating slide bar 105 causing a physically induced surge of fluid of suflicient velocity to be directed across the gaps of all contact pairs to extinguish the small arcs therebetween.

thus far described has assumed the pair of contacts to be separated substantially simultaneously. By slight modification the separation of the contacts may be made sequential as is preferred in certain installations, for example, by causing the generating contacts to first separate a predetermined amount prior to the initial separation of the interrupting contacts. In this manner a blast of fluid may be directed toward and be effective at the interrupting contacts prior to their initial separation.

To accomplish the above referred sequential interruption it is only necessary to incorporate a dimensional change in the slots 80, 81 of the rod 70 of a pair of mating contact members. For example, referring to the contact members 51 and 52 illustrated in Fig. 4, by terminating the extremities 84 of the slots 80, 81 at a point nearer the tip 71 of the contact member, during the interruption cycle the bar 82 will engage the extremities 84 at an instant of time prior to comparable engagement in the interrupting pair of contacts 53 and 54. Modification to accomplish a like result may be made by lengthening the slots 80, 81 of the interrupting contact member pairs 53 and 54.

The fluid blast generated by the are intermediate the generating contacts while being directed downwardly through the passage 42 actually traverses the plurality of baffled passages 43. Referring to Fig. 11 the portion of the passage 43 directly below the contact-receiving opening 216 comprises the expanded chambers 226 each of which embraces a considerable volume of dielectric fluid. During the interruption cycle the gas bubble will tend to move downwardly into the upper chamber 226 and in expanding rapidly results in a jet surge of fluid directed to the interrupting pair of contacts. As the interrupting contacts progressively separate the tips 71 thereof enter fresh pools of surging fluid as conveyed by the baffled passages 43 which tends to minimize the hot spot normally attendant a stationary contact.

The multiple break circuit interrupter herein described in its novel arrangement of constituents and combination of parts provides in addition to the advantages set forth above a unit of positive action and simplicity. The bridging member intermediate each adjacent pair of arcquenching members, and the lift rod therefor, may be relatively non-vacillating due to the single-blade construction. Further, in this connection, as the contacts of the bridging member engage the foot at the lower extremity of the slide bar considerably more latitude of tolerance for purposes of alignment may be permitted than would otherwise be required were the interrupting or generating contacts affixed direct to the lift rod for positive movement as is the practice in many conventional circuitbreakers.

While the invention that has been illustrated and described is now regarded as the preferred embodiment, the construction is, of course, subject to modifications without departing from the spirit and scope of the invention.

not desired to restrict the invention to the of construction illustrated and described, fall within the It is, therefore, particular form but to cover all modifications that may scope of the appended claims.

I claim as my invention:

1. A circuit-breaker adapted to interrupt a circuit by extinguishing an arc in a zone containing a dielectric fluid having in combination: a housing providing a space for containing said fluid; an arc-quenching member immersed in said fluid providing a main longitudinal passage comprising said zone, said passage extending in a substantially vertical direction and opening at one end thereof into said space; pump means disposed at the other end of said passage adapted to normally communicate said other end of said passage with said space and adapted to decrease the volume of said passage during interruption of said circuit; a pair of contact members connected to said circuit normally engaging each other in said zone to close said circuit; retraction means for movably mounting at least one of said contact members for movement away from said other contact member to form a gap therebetween; and interengaging means operatively connecting said retraction means and said pump means and actuable in one direction to move said retraction means to form said gap and to decrease the volume of said passage so as to deliver a downward stream of dielectric fluid to said 2. A circuit-breaker adapted to interrupt a circuit by extinguishing an arc in a zone containing a dielectric fluid having in combination: a housing providing a space for containing said fluid; an arc-quenching member immersed in said fluid providing a main longitudinal passage comprising said zone, said passage extending in a substantially vertical direction and opening at the lower end thereof into said space; pump means disposed at the upper end of said passage including a movable element adapted to move inwardly to decrease the volume of said passage the interruption cycle of said circuit; at least two pairs of contact members connected to said circuit each pair normally engaging in said zone to close said circuit, said pairs being space longitudinally of said passage; retraction means for each of said pairs of contact members for movably mounting at least one of its said contact members for movement away from its said other contact member for forming an arc therebetween in said zone upon interruption of said circuit; vent means for said pump means providing a normally open flue communicating the upper end of said passage to said space whereby to permit upward thermal flow of said fluid in said passage to lave said contact members; closure means for said vent means adapted to seal said flue upon upward relative fluid flow in said passage with respect to said pump means movable element in excess of said thermal flow; and interengaging means operatively connecting said retraction means and said pump means and actuable in one direction to move said retraction means to form said arcs and to decrease the volume of said passage, whereby inward movement of said pump means movable element initiates said relative fluid flow to close said flue so as to deliver a downward stream of dielectric fluid to said arcs.

3. A circuit-breaker adapted to interrupt a circuit by extinguishing an arc in a zone containing a dielectric fluid having in combination: a housing providing a space for containing said fluid; a conductor insulating bushing mounted to said housing and downwardly disposed thereinto for communicating a conductor into said space; an arc-quenching member secured to the lower end of said bushing and providing a main longitudinal passage comprising said zone, said passage extending in a substantially vertical direction and opening at the lower end thereof into said space; pump means disposed at the upper end of said passage having a movable element adapted to move inwardly to decrease the volume of said passage during the interruption cycle of said circuit; at least two pairs of contact members connected to said circuit each pair normally engaging in said zone to close said circuit, said pairs being spaced longitudinally of said passage; retraction means for each of said pairs of contact members for movably mounting at least one of its said contact members for movement away from its said other contact member for forming an arc therebetween' in said zone upon interruption of said circuit; interengaging means operatively connecting said vent means adapted to seal said flue upon fluid fl quenching memb providing a main longitudinal arc, said pump means providing a mechanically induced to be directed to all of said arcs. 5. A combination as defined in claim 4,

pair normally engaging in said zone to gas generate d by the means responding to s d to be said arcs.

eal said flue to said circuit, said pairs being spaced longitudinally 1on means for each of said pairs aid circuit, by pressure of uppermost of said arcs will induce ends of said cause a blast of said directed downwardly to the lowermost of municating the upper end of said passage with said space said passage of said fluid in to lave said contact members. 9. A combination a s defined in claim 8, said vent losure means adapted to seal said flue pump means movable element.

tion connection of bination a s defined in claim 7, the lost-mo- References Cited in the file of this patent UNITED Baker Leeds Bartlett STATES PATENTS Dec. 17, 1946 June 17, 1947 Aug. 5, 1952 

